Technical Abstract:
Fiber digestibility increases when pigs are fed for longer periods of time, suggesting an adaptation of intestinal microbiota with increased concentrations of fiber utilizing bacteria. We investigated whether feeding fiber utilizing bacteria to pigs would result in improved fiber digestion and reduce fecal output. Treatments were arranged as a 2 x 4 factorial with 2 diets and 4 bacterial treatments. Pigs, housed as 2 groups of 24, were fed either conventional or 20% distillers dried grains with solubles + 10% soybean hulls diet ad libitum with free water access. Treatments consisted of no bacteria (A) or one of three <i>Bacteroides</i> isolates (B, C and D); isolated from fecal enrichments with cellulose and xylan. Bacteria were fed to pigs once daily (0900 h) using a 50:50 mixture of bacteria in growth medium and food grade glycerol (dosage of 10^{10}^ bacterial cells/d). After 3 weeks, 24 pigs, at a time, were moved into metabolism crates for 11 d. On d 7 to 11 total dietary intake, fecal output, and urinary output were measured and feed, feed refusals and feces were sampled in order to determine nutrient digestibilities. Blood was taken on d 1 and 11 in order to analyze plasma for energy metabolites. Data were analyzed as 2 x 2 x 4 randomized block design with 2 groups of pigs, 2 dietary treatments and 4 bacterial treatments; no interactions were significant and these were removed from final model. Initial pig BW averaged 61.1 kg, after 50 d the final pig BW averaged 103.6 kg. Feed intake was not affected by diet or bacterial treatment. The effects of increased fiber in the diet were as expected. Fecal output (g/d, P = 0.13) and fecal output/intake (g/g, P = 0.07) were decreased when treatment B (by 19.8% and 19.4%, respectively) was fed compared to no bacteria (A). Treatment B also improved ADF digestibility when compared to A (by 10.0%, P= 0.37). Plasma glucose (mg/dL, P = 0.10) and cholesterol (mg/dL, P = 0.14) were increased in pigs fed B compared to no bacteria (A) by 5.3 and 10.4%, respectively. Bacterial treatment B demonstrated promise as a method to improve utilization of high fiber diets fed to pigs while maintaining performance.